Some Optical Properties of Thin Evaporated Cd₃As₂ Films

Abstract

The refractive index and absorption coefficient of thin evaporated Cd,Asa films are determinded from spectrophotometric transmission and reflection measurements over the range 0.5 to 12 vm. The refractive index of Cd,Aa, is 4.6 at L = 12 pm; at A = 1.9 pm a maximum index of nmax = 5.3 is observed. I n the spectral region 0.5 to 2 pm a sharp decrease is observed in the absorption coefficient, of about two orders of magnitude, from lo5 cm-l to los cm-1, which may be due to direct transitions. In the range 6 to 12 pm, the

Semiconducting Compounds of the AII BV Group

“…These results do not, however, confirm the presence of the second conduction band; if such a band exists, it lies at energies much higher than the values corresponding to the proposed ""E12 and it does not take part in transport phenomena. This assumption seems to be confirmed by optical transmission measurements on thin films (118,136) and may be consistent with the model proposed in (108) (see Figure 5b). Applying pressures higher than 25 kbar leads to a phase transition in Cd3As2 (113).…”

“…THIN Cd3Asz FILMS The earliest report on the properties of thin films of Cd3Asz was given in (116); more complete investigations are described in (117)(118)(119) and then confirmed by other authors (120,127,128). Since the vapor pressures of Cd, As, and Cd3Asz are rather high and of nearly the same order at the melting point of Cd3Asz (117), direct evaporation has been used to prepare the films a. c in a vacuum of the order 10-5 Torr onto glass, mica, NaCl, KCl (117,120,130), and also BaTi03 and SbSI (128) substrates held at temperatures 20 to 220°e.…”

“…The interaction of a-Cd3As2 films with the electron beam inside an electron microscope or the annealing of such films in a vacuum chamber at temperatures above ta � 400DC leads to crystallization effects resulting in a very well ordered film structure and a distinct rise in the carrier mobility (135). Optical transmission and reflection measurements for wavelengths in the range O.l�1.5 eV have been reported (118,136) (Figure 10). High values of the absorption coefficient C( up to 105 of energies (1.4--0 .8 eV) have been observed and attributed by the authors (118,136) to direct transitions in Cd3As2.…”

“…Optical transmission and reflection measurements for wavelengths in the range O.l�1.5 eV have been reported (118,136) (Figure 10). High values of the absorption coefficient C( up to 105 of energies (1.4--0 .8 eV) have been observed and attributed by the authors (118,136) to direct transitions in Cd3As2. According to the band model proposed in (78), this strong absorption edge may be due to the transition from the 'heavy valence band E(r I S) to the higher conduction band AI(X 1) (see Figure Sa).…”

Numerical simulation of a UV He—Ar—N2gas-discharge laser

“…According to the transmission and reflection studies that have been previously performed on Cd 3 As 2 thin films in the range of 0.1-1.2 eV, the energy separation between the minimum of the conduction band and maximum of the valence band lies in the range of 0.1-0.2 eV [8]. The strongest and lowest energy absorption identified at 0.11 eV can be thus attributed to direct E → A 1 type transitions in our samples.…”